Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for decipherin...Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for deciphering the geodynamic processes in subduction zones.In this study,we apply different versions of datasets(ds55 and ds62)and associated a-x relations to a wellestablished LT-HP eclogite at Huwan in the classic western Dabie orogen to constrain its P-T evolution.The eclogite comprises garnet+omphacite+amphibole+white mica+epidote+quartz+chlorite+rutile/ilmenite/sphene.Garnet porphyroblasts show mono-variation in the end members(spessartine from 17 mol%to 0,pyrope from 2 mol%to 18 mol%,almandine from 47 mol%to 64mol%and grossular from 35 mol%to 18 mol%)from core to rim.Phase diagrams combined with compositional isopleth thermobarometry show that dataset ds62 and associated a-x relations yield P_(max)of~33 kbar at~560℃,conflicting with our petrological observations and previous studies.On the other hand,phase equilibrium modeling using dataset ds62 and a revised symmetric garnet a-x model irrespective of Fe^(3+)(O)gives P_(max)of~27 kbar at~560℃,consistent with the results using dataset ds55 and associated a-x relations.Therefore,we recommend a symmetric model for garnet involving py,alm,gr and spss,without Fe~(3+)components,instead of the asymmetric garnet a-x relations involving py,alm,gr,spss and kho by White et al.(2014),for calculating phase diagrams for LT-(U)HP eclogite when using dataset ds62.In this study,the defined P-T path is characterized by a segment of the prograde evolution showing a first moderate slope,followed by gentle then steep slopes,representing the thermal structure evolution recorded by slab surface during continental subduction.Our work combined with previous studies conclude that in western Dabie,the Huwan HP eclogite belt to the north and the Hong'an HP eclogite belt to the south belong to the same HP slice overlying the Xinxian UHP slice.展开更多
Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concer...Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO_(2)-unsaturation.In this paper,the SiO_(2) activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO_(2) activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO_(2) activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO_(2) activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO_(2) activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO_(2)-bearing fluid,the addition of SiO_(2) can increase its activity and make zircon stable at low temperatures.The SiO_(2) activity in ultrabasic-basic rocks is not only positively correlated with the SiO_(2) content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO_(2),decreasing the SiO_(2) activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.展开更多
Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual c...Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual cell.The properties of critical point were obtained by extrapolation.The results showed that critical temperature,critical pressure and critical compressibility factor of CO2-isobutanol system decreased with the increase of critical CO2 content.The phase equilibrium model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation,and model parameters were determined by optimization calculation of nonlinear least square method.The correlation between calculated values and the experimental data showed good agreement.展开更多
The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western Mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and migmatites.However,...The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western Mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and migmatites.However,the pressure-temperature(P-T)conditions of metamorphism and partial melting remain poorly studied in the region.To elucidate metamorphic P-T conditions,phase equilibrium modelling was applied to two sillimanite-garnet paragneisses,one amphibole-orthogneiss,and one amphibolite.Sillimanite-garnet paragneisses exhibit a lepidoblastic texture with a biotite+sillimanite+kyanite+garnet+quartz+plagioclase+K-feldspar mineral assemblage.Amphibole-orthogneiss and amphibolite display a nematoblastic texture with an amphibole+(1)plagioclase+quartz+(1)titanite assemblage and an amphibole+(2)plagioclase+(2)titanite+ilmenite retrograde mineral assemblage.Pseudosections calculated for the two sillimanite-garnet paragneiss samples show P-T peak conditions at~6-7.5 kbar and~725-740℃.The results for amphibole-orthogneiss and the amphibolite yield P-T peak conditions at~8.5-10 kbar and~690-710℃.The mode models imply that metasedimentary and metaigneous units can produce up to~20 vol%and~10 vol%of melt,respectively.Modelling within a closed system during isobaric heating suggests that melt compositions of metasedimentary and metaigneous units are likely to have direct implications for the petrogenesis of the Puerto Vallarta Batholith.Our new data indicate that the Yelapa-Chimo Metamorphic Complex evolved through a metamorphic gradient between~23-33℃km^-1and the metamorphic rocks formed at depths between~22 km and~30 km with a burial rate of~2.0 km Ma^-1.Finally,the P-T data for both metasedimentary and metaigneous rocks provide new constraints on an accretionary framework,which is responsible for generating metamorphism and partial melting in the YelapaChimo Metamorphic Complex during the Early Cretaceous.展开更多
The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The r...The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The result demonstrated DMT/DMI and DMT/DMP systems are eutectic while DMI/DMP is a solid-solution system. The eutectic temperature of DMT/DMI system is 336.7 K and that of DMT/DMP is 271.1 K. Furthermore, a classical solid-liquid phase equilibrium model was used to fit the experimental data of the eutectic systems of DMT/DMI and DMT/ DMP and the theoretical model could describe the eutectic solid-liquid phase diagrams properly.展开更多
Ultrahigh-pressure（UHP） metamorphic rocks are distinctive products of crustal deep subduction,and are mainly exposed in continental subduction-collision terranes. UHP slices of continental crust are usually involved...Ultrahigh-pressure（UHP） metamorphic rocks are distinctive products of crustal deep subduction,and are mainly exposed in continental subduction-collision terranes. UHP slices of continental crust are usually involved in multistage exhumation and partial melting, which has obvious influence on the rheological features of the rocks, and thus significantly affect the dynamic behavior of subducted slices. Moreover,partial melting of UHP rocks have significant influence on element mobility and related isotope behavior within continental subduction zones, which is in turn crucial to chemical differentiation of the continental crust and to crust-mantle interaction.Partial melting can occur before, during or after the peak metamorphism of UHP rocks. Post-peak decompression melting has been better constrained by remelting experiments; however, because of multiple stages of decompression, retrogression and deformation, evidence of former melts in UHP rocks is often erased. Field evidence is among the most reliable criteria to infer partial melting. Glass and nanogranitoid inclusions are generally considered conclusive petrographic evidence. The residual assemblages after melt extraction are also significant to indicate partial melting in some cases. Besides field and petrographic evidence, bulk-rock and zircon trace-element geochemical features are also effective tools for recognizing partial melting of UHP rocks. Phase equilibrium modeling is an important petrological tool that is becoming more and more popular in P-T estimation of the evolution of metamorphic rocks; by taking into account the activity model of silicate melt, it can predict when partial melting occurred if the P-T path of a given rock is provided.UHP silicate melt is commonly leucogranitic and peraluminous in composition with high SiO_2,low MgO, FeO, MnO, TiO_2 and CaO, and variable K_2 O and Na_2 O contents. Mineralogy of nanogranites found in UHP rocks mainly consists of plagioclase ＋ K-feldspar ＋ quartz, plagioclase being commonly albite-rich.Trace element pattern of the melt is characterized by significant enrichment of large ion lithophile elements（LILE）, depletion of heavy rare earth elements（HREE） and high field strength elements（HFSE）,indicating garnet and rutile stability in the residual assemblage. In eclogites, significant Mg-isotope fractionation occurs between garnet and phengite; therefore, Mg isotopes may become an effective indicator for partial melting of eclogites.展开更多
The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite s...The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dating.The schist is mainly composed of garnet,biotite,plagioclase,quartz,rutile,and ilmenite.Phase equilibrium modeling revealed the peak metamorphic conditions of 8-9 kbar and 635-675°C.By further integrating the prograde metamorphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure during the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak metamorphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.展开更多
A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO2 at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015＆#21...A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO2 at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015＆#215;10^-3 to 3.261＆#215;10^-3 and correlated by using seven different semi empirical equations of state （Bartle, Modi-fied Bartle, Mendez-Teja, Modified Mendez-Teja, Kumar-Johnson, Sung-shim and Gordillo） as well as seven cubic equations of state （van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, Stryjek-Vera, Patel-Teja-Valderana and Pazuki）. Single and twin-parametric van der Walls mixing rules （vdW1, vdW2） were ap-plied in order to estimate the supercritical solution properties. The physicochemical properties were also obtained using Joback, Lydersen and Ambrose methods. Absolute average relatives deviation （AARD） were calculated and compared for all the correlating systems. Results showed that among the cubic equations of state （EOSs） the Pazuki equation （AARD=19.85% using vdW1 and AARD=8.79% using vdW2） and SRK equation （AARD=19.20%using vdW1 and AARD=10.03%using vdW2） predicted the ibuprofen solubility in supercritical CO2 with the least error in comparison to the others. Among the semi-empirical EOSs the most desirable deviation （AARD〈10%） was obtained by using Modified Bartle and Modified Mendez-Teja equations in all the studied temperatures.展开更多
Rising energy costs and growing environmental awareness motivate a critical revision of the design of distillation units. Systematic design techniques, such as the rectification body, column profile map, and temperatu...Rising energy costs and growing environmental awareness motivate a critical revision of the design of distillation units. Systematic design techniques, such as the rectification body, column profile map, and temperature collocation methods, require exact knowledge of all pinch points in a particular system, because these stationary points delineate the possible composition trajectories realizable in separation columns. This paper demonstrates novel methods for rigorously determining all pinch points for the constant relative volatility, ideal and non-ideal systems. Constant relative volatility and ideal solution systems are transformed into one-dimensional polynomial and nonlinear functions, regardless of the number of the components. A deflation method is proposed to locate all zeros in ideal and non-ideal zeotropic problems. For more challenging non-ideal problems, a novel hybrid sequential niche algorithm is used to solve hard azeotropic problems successfully. Finally, the design implications of these pinch point locations are investigated to show how new separation configurations can be devised. Methodically the paper points out the use of rigorous pinch point computations in conjunction with continuous composition profiles for robust distillation design.展开更多
基金financially supported by the National Natural Science Foundation of China(No.41930215)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)。
文摘Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for deciphering the geodynamic processes in subduction zones.In this study,we apply different versions of datasets(ds55 and ds62)and associated a-x relations to a wellestablished LT-HP eclogite at Huwan in the classic western Dabie orogen to constrain its P-T evolution.The eclogite comprises garnet+omphacite+amphibole+white mica+epidote+quartz+chlorite+rutile/ilmenite/sphene.Garnet porphyroblasts show mono-variation in the end members(spessartine from 17 mol%to 0,pyrope from 2 mol%to 18 mol%,almandine from 47 mol%to 64mol%and grossular from 35 mol%to 18 mol%)from core to rim.Phase diagrams combined with compositional isopleth thermobarometry show that dataset ds62 and associated a-x relations yield P_(max)of~33 kbar at~560℃,conflicting with our petrological observations and previous studies.On the other hand,phase equilibrium modeling using dataset ds62 and a revised symmetric garnet a-x model irrespective of Fe^(3+)(O)gives P_(max)of~27 kbar at~560℃,consistent with the results using dataset ds55 and associated a-x relations.Therefore,we recommend a symmetric model for garnet involving py,alm,gr and spss,without Fe~(3+)components,instead of the asymmetric garnet a-x relations involving py,alm,gr,spss and kho by White et al.(2014),for calculating phase diagrams for LT-(U)HP eclogite when using dataset ds62.In this study,the defined P-T path is characterized by a segment of the prograde evolution showing a first moderate slope,followed by gentle then steep slopes,representing the thermal structure evolution recorded by slab surface during continental subduction.Our work combined with previous studies conclude that in western Dabie,the Huwan HP eclogite belt to the north and the Hong'an HP eclogite belt to the south belong to the same HP slice overlying the Xinxian UHP slice.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41972067&41930215)the Fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources(Grant No.J1901-11).
文摘Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO_(2)-unsaturation.In this paper,the SiO_(2) activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO_(2) activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO_(2) activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO_(2) activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO_(2) activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO_(2)-bearing fluid,the addition of SiO_(2) can increase its activity and make zircon stable at low temperatures.The SiO_(2) activity in ultrabasic-basic rocks is not only positively correlated with the SiO_(2) content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO_(2),decreasing the SiO_(2) activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.
文摘Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual cell.The properties of critical point were obtained by extrapolation.The results showed that critical temperature,critical pressure and critical compressibility factor of CO2-isobutanol system decreased with the increase of critical CO2 content.The phase equilibrium model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation,and model parameters were determined by optimization calculation of nonlinear least square method.The correlation between calculated values and the experimental data showed good agreement.
基金funded by Programa de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica(PAPIIT)grant IN112314。
文摘The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western Mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and migmatites.However,the pressure-temperature(P-T)conditions of metamorphism and partial melting remain poorly studied in the region.To elucidate metamorphic P-T conditions,phase equilibrium modelling was applied to two sillimanite-garnet paragneisses,one amphibole-orthogneiss,and one amphibolite.Sillimanite-garnet paragneisses exhibit a lepidoblastic texture with a biotite+sillimanite+kyanite+garnet+quartz+plagioclase+K-feldspar mineral assemblage.Amphibole-orthogneiss and amphibolite display a nematoblastic texture with an amphibole+(1)plagioclase+quartz+(1)titanite assemblage and an amphibole+(2)plagioclase+(2)titanite+ilmenite retrograde mineral assemblage.Pseudosections calculated for the two sillimanite-garnet paragneiss samples show P-T peak conditions at~6-7.5 kbar and~725-740℃.The results for amphibole-orthogneiss and the amphibolite yield P-T peak conditions at~8.5-10 kbar and~690-710℃.The mode models imply that metasedimentary and metaigneous units can produce up to~20 vol%and~10 vol%of melt,respectively.Modelling within a closed system during isobaric heating suggests that melt compositions of metasedimentary and metaigneous units are likely to have direct implications for the petrogenesis of the Puerto Vallarta Batholith.Our new data indicate that the Yelapa-Chimo Metamorphic Complex evolved through a metamorphic gradient between~23-33℃km^-1and the metamorphic rocks formed at depths between~22 km and~30 km with a burial rate of~2.0 km Ma^-1.Finally,the P-T data for both metasedimentary and metaigneous rocks provide new constraints on an accretionary framework,which is responsible for generating metamorphism and partial melting in the YelapaChimo Metamorphic Complex during the Early Cretaceous.
文摘The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The result demonstrated DMT/DMI and DMT/DMP systems are eutectic while DMI/DMP is a solid-solution system. The eutectic temperature of DMT/DMI system is 336.7 K and that of DMT/DMP is 271.1 K. Furthermore, a classical solid-liquid phase equilibrium model was used to fit the experimental data of the eutectic systems of DMT/DMI and DMT/ DMP and the theoretical model could describe the eutectic solid-liquid phase diagrams properly.
基金financially supported by the National Basic Research Program of China (Grant No. 2015CB856104)the National Natural Science Foundation of China (Grant No. 41273036)
文摘Ultrahigh-pressure（UHP） metamorphic rocks are distinctive products of crustal deep subduction,and are mainly exposed in continental subduction-collision terranes. UHP slices of continental crust are usually involved in multistage exhumation and partial melting, which has obvious influence on the rheological features of the rocks, and thus significantly affect the dynamic behavior of subducted slices. Moreover,partial melting of UHP rocks have significant influence on element mobility and related isotope behavior within continental subduction zones, which is in turn crucial to chemical differentiation of the continental crust and to crust-mantle interaction.Partial melting can occur before, during or after the peak metamorphism of UHP rocks. Post-peak decompression melting has been better constrained by remelting experiments; however, because of multiple stages of decompression, retrogression and deformation, evidence of former melts in UHP rocks is often erased. Field evidence is among the most reliable criteria to infer partial melting. Glass and nanogranitoid inclusions are generally considered conclusive petrographic evidence. The residual assemblages after melt extraction are also significant to indicate partial melting in some cases. Besides field and petrographic evidence, bulk-rock and zircon trace-element geochemical features are also effective tools for recognizing partial melting of UHP rocks. Phase equilibrium modeling is an important petrological tool that is becoming more and more popular in P-T estimation of the evolution of metamorphic rocks; by taking into account the activity model of silicate melt, it can predict when partial melting occurred if the P-T path of a given rock is provided.UHP silicate melt is commonly leucogranitic and peraluminous in composition with high SiO_2,low MgO, FeO, MnO, TiO_2 and CaO, and variable K_2 O and Na_2 O contents. Mineralogy of nanogranites found in UHP rocks mainly consists of plagioclase ＋ K-feldspar ＋ quartz, plagioclase being commonly albite-rich.Trace element pattern of the melt is characterized by significant enrichment of large ion lithophile elements（LILE）, depletion of heavy rare earth elements（HREE） and high field strength elements（HFSE）,indicating garnet and rutile stability in the residual assemblage. In eclogites, significant Mg-isotope fractionation occurs between garnet and phengite; therefore, Mg isotopes may become an effective indicator for partial melting of eclogites.
基金supported by the National Natural Science Foundation of China(Grant Nos.42162012,42072094)the Key Laboratory of Sanjiang Metallogeny and Resource Exploration and Utilization,Ministry of Natural Resources(Project No.ZRZYBSJSYS2022001).
文摘The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dating.The schist is mainly composed of garnet,biotite,plagioclase,quartz,rutile,and ilmenite.Phase equilibrium modeling revealed the peak metamorphic conditions of 8-9 kbar and 635-675°C.By further integrating the prograde metamorphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure during the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak metamorphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.
文摘A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO2 at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015＆#215;10^-3 to 3.261＆#215;10^-3 and correlated by using seven different semi empirical equations of state （Bartle, Modi-fied Bartle, Mendez-Teja, Modified Mendez-Teja, Kumar-Johnson, Sung-shim and Gordillo） as well as seven cubic equations of state （van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, Stryjek-Vera, Patel-Teja-Valderana and Pazuki）. Single and twin-parametric van der Walls mixing rules （vdW1, vdW2） were ap-plied in order to estimate the supercritical solution properties. The physicochemical properties were also obtained using Joback, Lydersen and Ambrose methods. Absolute average relatives deviation （AARD） were calculated and compared for all the correlating systems. Results showed that among the cubic equations of state （EOSs） the Pazuki equation （AARD=19.85% using vdW1 and AARD=8.79% using vdW2） and SRK equation （AARD=19.20%using vdW1 and AARD=10.03%using vdW2） predicted the ibuprofen solubility in supercritical CO2 with the least error in comparison to the others. Among the semi-empirical EOSs the most desirable deviation （AARD〈10%） was obtained by using Modified Bartle and Modified Mendez-Teja equations in all the studied temperatures.
文摘Rising energy costs and growing environmental awareness motivate a critical revision of the design of distillation units. Systematic design techniques, such as the rectification body, column profile map, and temperature collocation methods, require exact knowledge of all pinch points in a particular system, because these stationary points delineate the possible composition trajectories realizable in separation columns. This paper demonstrates novel methods for rigorously determining all pinch points for the constant relative volatility, ideal and non-ideal systems. Constant relative volatility and ideal solution systems are transformed into one-dimensional polynomial and nonlinear functions, regardless of the number of the components. A deflation method is proposed to locate all zeros in ideal and non-ideal zeotropic problems. For more challenging non-ideal problems, a novel hybrid sequential niche algorithm is used to solve hard azeotropic problems successfully. Finally, the design implications of these pinch point locations are investigated to show how new separation configurations can be devised. Methodically the paper points out the use of rigorous pinch point computations in conjunction with continuous composition profiles for robust distillation design.
